Rather than "nuclear codes" that the President has memorized, there are several components in action when it comes time to destroy a country/continent/planet in one fell swoop: Codes and the Football. One set of codes are printed onto a card called "the biscuit" and given to the President as self-identification, like a password, Brookings reports. These are used in conjunction with the "Football," a 45-pound briefcase containing everything one on-the-go Destroyer of Worlds needs to verify the president's identity and command an attack, including communications equipment and nuclear strike options, according to Smithsonian Magazine. A different set of codes, generated by the NSA, stay in military custody at the Pentagon and various other locations around the country. These are the codes that actually hold the power, since the military can carry out an attack in the event that the President or a successor can't authorize it themselves.